Rediscover Pope John XXIII's extraordinary vision for world peace in this fortieth anniversary edition of his historic encyclical. "Peace on earth," Pope John XXIII first wrote in 1962, "can never be established, never guaranteed, except by the diligent observance of the divinely established order." And in this timeless encyclical, he assuredly guides the faithful in the journey toward peace, directed by God Himself, working together for the benefit of the whole human race.